Retene

Retene, methyl isopropyl phenanthrene or 1-methyl-7-isopropyl phenanthrene, C₁₈H₁₈, is a polycyclic aromatic hydrocarbon present in the coal tar fraction, boiling above 360 °C. It occurs naturally in the tars obtained by the distillation of resinous woods. It crystallizes in large plates, which melt at 98.5 °C and boil at 390 °C. It is readily soluble in warm ether and in hot glacial acetic acid. Sodium and boiling amyl alcohol reduce it to a tetrahydroretene, but if it heated with phosphorus and hydriodic acid to 260 °C, a dodecahydride is formed. Chromic acid oxidizes it to retene quinone, phthalic acid and acetic acid. It forms a picrate that melts at 123-124 °C.

Retene

Skeletal formula
Ball-and-stick model
Names
Preferred IUPAC name 1-Methyl-7-(propan-2-yl)phenanthrene
Other names Retene
Identifiers
CAS Number	483-65-8 Y
3D model (JSmol)	Interactive image
ChemSpider	9805 N
ECHA InfoCard	100.006.908
EC Number	207-597-9
PubChem CID	10222
UNII	0W2D2E1P9Q Y
CompTox Dashboard (EPA)	DTXSID7058701
InChI InChI=1S/C18H18/c1-12(2)14-7-10-17-15(11-14)8-9-16-13(3)5-4-6-18(16)17/h4-12H,1-3H3 N Key: NXLOLUFNDSBYTP-UHFFFAOYSA-N N InChI=1/C18H18/c1-12(2)14-7-10-17-15(11-14)8-9-16-13(3)5-4-6-18(16)17/h4-12H,1-3H3 Key: NXLOLUFNDSBYTP-UHFFFAOYAL
SMILES Cc1cccc3c1ccc2cc(C(C)C)ccc23
Properties
Chemical formula	C18H18
Molar mass	234.33552
Melting point	98.5 °C (209.3 °F; 371.6 K)
Boiling point	390 °C (734 °F; 663 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

Retene is derived by degradation of specific diterpenoids biologically produced by conifer trees. The presence of traces of retene in the air is an indicator of forest fires; it is a major product of pyrolysis of conifer trees.^{[1][failed verification – see discussion]} It is also present in effluents from wood pulp and paper mills.^[2]

Retene, together with cadalene, simonellite and ip-iHMN, is a biomarker of vascular plants, which makes it useful for paleobotanic analysis of rock sediments. The ratio of retene/cadalene in sediments can reveal the ratio of the genus Pinaceae in the biosphere.^[3]

Health effects

A recent study has shown retene, which is a component of the Amazonian organic PM10, is cytotoxic to human lung cells.^[4]